Chapter 8 Prototyping and Rapid Application Development

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Dec 2, 2013 (3 years and 7 months ago)

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Chapter 8

Prototyping and Rapid

Application Development

Systems Analysis and Design

Kendall and Kendall

Fifth Edition

Kendall & Kendall


Copyright © 2002 by Prentice Hall, Inc.

8
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Major Topics


Prototyping concepts


Types of prototypes


Prototyping and the systems
development life cycle


Prototype development guidelines


Prototype evaluation


Rapid application development (RAD)

Kendall & Kendall


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Prototyping


Prototyping is an information
-
gathering
technique


Prototypes are useful in seeking user
reactions, suggestions, innovations, and
revision plans


Prototyping may be used as an
alternative to the systems development
life cycle

Kendall & Kendall


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Initial User Reactions


Reactions must be gathered from users


There are three types


User suggestions


Innovations


Revision plans

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Four Kinds of Prototypes


There are four conceptions of
prototypes:


Patched
-
up prototype


Non
-
operational scale model


First full
-
scale model


Prototype which contain only some of the
essential system features

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Patched
-
up Prototype


This is a working model with all the
features but is inefficient


Users can interact with the system


Storage and retrieval of data may be
inefficient


Workable but inefficient


May contain only basic features

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Nonoperational Scale Models


A nonoperational scale mode is one
which is not operational, except for
certain features to be tested


Prototype input and output

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First Full
-
Scale Models


Create a pilot system


An operation model


Useful when many installations of the
same information system are planned


An example is a system to be installed
in one location, tested and modified as
necessary, and later implemented in
other locations

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Selected Features Prototype


An operational model that includes
some, but not all, of the final system
features


With the acceptance of these features,
later essential features are added


Some menu items are available


System is built in modules


These are part of the actual system

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Prototyping As an Alternative
to the Systems Life Cycle


Two main problems with the SDLC


Extended time required to go through the
development life cycle


User requirements change over time


Prototyping may be used as an alternative

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Prototype Development
Guidelines


Guidelines for developing a prototype
are


Work in manageable modules


Build the prototype rapidly


Modify the prototype in successive
iterations


Stress the user interface

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Prototype Advantages


Potential for changing the system early
in its development


Opportunity to stop development on an
unworkable system


Possibility of developing a system that
closely addresses users' needs and
expectations

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Prototype Disadvantages


Managing the prototyping process is
difficult because of its rapid, iterative
nature


Requires feedback on the prototype


Incomplete prototypes may be regarded
as complete systems

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Prototype Evaluation


Systems analysts must work
systematically to elicit and evaluate
users' reactions to the prototype


Three ways the user is involved


Experimenting with the prototype


Giving open reactions to the prototype


Use a prototype evaluation form


Suggesting additions to and/or deletions
from the prototype

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Prototyping on the Web


Prototyping on the Web can help to
facilitate the prototyping process by


Allowing users at a distance review the
prototype and send comments


Allowing users to review the prototype
when they have time, and on any machine
that has Internet capabilities


The analyst does not have to install the
software on the user’s computer

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Rapid Application Development
(RAD)


RAD, or rapid application development,
is an object
-
oriented approach to
systems development that includes a
method of development as well as
software tools

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RAD Phases


There are three broad phases to RAD:


Requirements planning


RAD design workshop


Implementation

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Requirements Planning Phase


Users and analysts meet to identify
objectives of the application or system


Oriented toward solving business
problems

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RAD Design Workshop


Design and refine phase


Use group decision support systems to
help users agree on designs


Programmers and analysts can build and
show visual representations of the designs
and workflow to users


Users respond to actual working prototypes


Analysts refine designed modules based on
user responses

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Implementation Phase


As the systems are built and refined,
the new systems or partial systems are
tested and introduced to the
organization


When creating new systems, there is no
need to run old systems in parallel

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Martin Approach to RAD


The Martin approach to RAD includes
four phases:


Requirements planning


User design


Construction


Cutover

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RAD and the SDLC


RAD tools are used to generate screens
and exhibit the overall flow of the
application


Users approve the design and sign off
on the visual model


Implementation is less stressful since
users helped to design the business
aspects of the system

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When to Use RAD


RAD is used when


The team includes programmers and
analysts who are experienced with it


There are pressing reasons for speeding up
application development


The project involves a novel ecommerce
application and needs quick results


Users are sophisticated and highly engaged
with the goals of the company

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Using RAD Within the SDLC


RAD is very powerful when used within
the SDLC


It can be used as a tool to update,
improve, or innovate selected portions
of the system

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Disadvantages of RAD


May try and hurry the project too much


Loosely documented


May not address pressing business
problems


Potentially steep learning curve for
programmers inexperienced with RAD
tools